JPH06203320A - Erasing head - Google Patents

Abstract

PURPOSE:To suppress heating up by eddy current so as not to damage a magnetic recording medium by constituting the erasing head in such a manner that erasing is surely executed by the uniform flow of magnetic fluxes MF to the respective magnetic layers of side cores by fringing and that the electric resistance as a whole of a center core is increased by the presence of nonmetallic and nonmagnetic layers. CONSTITUTION:The center core 1 wound with a coil is alternately laminated with the magnetic layers 6 consisting of a high saturation magnetic flux density material and the nonmetallic and nonmagnetic layers 7. The side cores 2, 3 are laminated with the magnetic layers 8 via several mum insulating layers 9. The thickness of the nonmagnetic layers 7 is <=50mum and the thickness of the magnetic layers 6, 8 is 50 to 20mum. The ratio of the thickness of the nonmagnetic layers 7 and the thickness of the magnetic layers 6, 9 is specified to (1:1) to (4:1).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an erase head.

[0002]

2. Description of the Related Art When recording on a magnetic recording medium (for example, a magnetic tape), the recording head or the recording / reproducing head is used prior to recording.
A method of erasing already recorded information by using an erasing head arranged upstream of a magnetic recording medium with respect to a reproducing head is widely adopted.

FIG. 11 shows an erasing head. This erasing head has a structure in which a prism-shaped center core 71 around which a coil 75 is wound and a pair of C-shaped side cores 72 and 73 arranged so as to sandwich the center core 71 are connected at a base portion. The end faces 77, 78 of the tip end portions of the side cores 72, 73 facing the center core 71 are narrow, and a magnetic gap 7 is formed at two locations between the end faces 77, 78 and both side faces on the tip end side of the center core 71.
4, 74 are formed. Such a double gap structure erasing head is used in a video tape recorder (VTR) and some audio tape decks.

In order to improve the performance of the erase head, it is effective to improve the magnetic characteristics of the core material (especially saturation magnetic flux density).
In addition to the above-mentioned device, the magnetic recording medium used in a specific printer needs to have a particularly high Hc (coercive force) in order to ensure record storage.

In order to erase information recorded on such a high Hc magnetic recording medium, a material showing an Hc of 2000 Oe or more must be used as the core material of the erasing head. As a result, a material having a high saturation magnetic flux density is required.

In the erase head of FIG. 11, each core 71, 72, 73
For example, ferrite is used as the material of the above, but a ferrite core cannot satisfy the above-mentioned demand because the saturation magnetic flux density is insufficient.

As magnetic materials having a high saturation magnetic flux density, there are sendust and amorphous magnetic alloys, but since these are metals, they have a low electric resistance and are energized in the coil so that the core (especially in the center core) Eddy current is generated, loss is large, and the amount of heat generated by the eddy current is large. Therefore, if the above-mentioned materials are used for the cores 71, 72, 73 of FIG. 11, not only the loss becomes large but also the amount of heat generation becomes large, which is not preferable for the apparatus (printer). In particular, the magnetic recording medium is disadvantageously damaged by heat.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and uses a material having a high saturation magnetic flux density for the core to maintain excellent erasing ability and prevent heat generation. The purpose is to provide an erase head.

[0009]

In order to achieve the above object, the present invention has the following constitution.

According to the first aspect of the present invention, at least the magnetic gap side tip of the wound core portion has a magnetic layer and a non-magnetic layer alternately arranged along the width direction of the magnetic gap. The erasing head has a laminated structure in which

According to a second aspect of the present invention, the thickness of the non-magnetic layer is 50 μm or less, and the ratio of the thickness of the magnetic layer to the thickness of the non-magnetic layer is (1: 1). ~ (4: 1) according to the erase head according to claim 1.

The invention according to claim 3 relates to the erasing head according to claim 1 or 2, wherein the erasing head has a center core portion and a side core portion, and the wound core portion is the center core portion. .

The invention according to claim 4 has a front core portion and a back core portion, and the center portion of the front core portion has the laminated structure according to claim 1.
Or, it relates to the erasing head described in 2.

According to a fifth aspect of the invention, at least the tip of the wound core portion on the magnetic gap side is made of a low loss material, and the core portion other than the low loss material portion is made of a high saturation magnetic flux density material. Of the erasing head.

The invention according to claim 6 has a front core portion and a back core portion, and the center portion of the front core portion is made of a low-loss material. Pertain to.

The invention according to claim 7 has a front core portion and a back core portion, and the center portion of the front core portion is made of a low-loss material. Pertain to.

[0017]

EXAMPLES Examples of the present invention will be described below.

FIG. 1 is a perspective view of the erase head, and FIG. 12 is an enlarged plan view of the periphery of the magnetic gap. This erase head
It has a structure in which a prism-shaped center core 1 around which a coil 5 is wound and a pair of C-shaped side cores 2 and 3 arranged so as to sandwich the center core 1 are connected at a base portion. The end faces 7 and 8 of the tip portions of the side cores 2 and 3 facing the center core 1 are narrow, and the end faces 7 and 8 and the center core 1 are narrowed.
Magnetic gaps 4 and 4 are formed at two locations between the both side surfaces on the tip side of the.

In the erase head using the core made of the high saturation magnetic flux density material, the temperature rises most in the center core where the magnetic flux is concentrated. Therefore, in this example, as shown in FIG. 2, the center core 1 is set to sendust (5% Al, 10% S
i, 85% Fe) and magnetic layers 6 and non-metal and non-magnetic layers 7 (glass layers) 7 are alternately laminated.

The layers 6 and 7 are laminated along the width direction of the magnetic gap so as to be exposed to the magnetic gaps 4 and 4. Sendust has a high saturation magnetic flux density, a high magnetic permeability, and zero magnetic anisotropy and magnetostriction, and is suitable as a core material. Instead of sendust, an amorphous magnetic alloy exhibiting similar magnetic characteristics may be adopted. The non-metal and non-magnetic layer 7 may be a layer made of ceramics, mica, or paper in addition to glass.

The side cores 2 and 3 are formed by laminating a magnetic layer 8 (made of the same material as the magnetic layer 6 of the center core) with an extremely thin insulating layer (for example, an adhesive layer) 9 having a thickness of several μm. .

FIG. 3 is a partially enlarged view of FIG. 2 showing a state of magnetic flux flowing from the center core 1 to the side cores 2 and 3 in the magnetic gaps 4 and 4. The magnetic flux MF emitted from the magnetic layer 6 of the center core 1 is generated by the opposing side cores 2 as shown by arrows.
3 toward the magnetic layer 8 and also obliquely toward the magnetic layer 8 facing the non-magnetic layer 7. In this way, the magnetic flux MF from the magnetic layer 6 of the center core 1 flows evenly to the magnetic layers 8 of the side cores 2 and 3. Such a phenomenon is called fringing (leakage magnetic flux), which is used to improve the erasing rate of the non-magnetic material portion.

In order to cause fringing, it is necessary to make the thickness of the nonmagnetic layer 7 sufficiently small. In this example,
The non-magnetic layer 7 has a thickness of 50 μm or less, and the magnetic layers 6 and 8 have a thickness of 50 to 200 μm. The magnetic gap 4,
The leakage magnetic flux for erasure that enters the magnetic recording medium at 4 is
Since it is formed in the direction perpendicular to the paper surface of FIG. 3, it does not appear in FIG.

Since the non-magnetic layer 7 of the center core 1 is made sufficiently thin with a thickness of 50 μm or less, fringing can be effectively caused. The magnetic layers 8 of the side cores 2 and 3 are laminated with an insulating layer 9 having a thickness of several μm, which is sufficiently thin, interposed therebetween.

The laminated structure composed of the magnetic layer 6 and the non-magnetic layer 7 of the center core 1 and the laminated structure composed of the magnetic layer 8 and the insulating layer 9 of the side cores 2 and 3 have respective layers (especially the magnetic layers 6 and 8).
Is achieved by sputtering.

By forming the center core 1 in the above-described laminated structure, the electric resistance of the whole center core is increased due to the existence of the non-metal non-magnetic layer 7, the eddy current at the time of erasing is reduced, and the heat generation due to this is reduced. To do. Therefore, the temperature rise near the magnetic gaps 4 and 4 is suppressed. In addition, the erasing rate is sufficient even in the erasing head for the printer due to the sendust magnetic layers 6 and 8 exhibiting the magnetic characteristics as described above.

The ratio of the thickness of the magnetic layer 6 of the center core 1 to the thickness of the non-magnetic layer 7 is preferably in the range of (1: 1) to (4: 1). If this ratio is less than 1: 1, the relative total cross-sectional area of the magnetic layer 6 becomes small and a sufficient erasing rate cannot be achieved. On the other hand, if the above ratio exceeds 4: 1, the relative total cross-sectional area of the magnetic layer 6 becomes large and the resistance to eddy current becomes small, so that the temperature rise near the magnetic gap cannot be sufficiently prevented.

The center core may have a laminated structure as described above only in the portion on the magnetic gap side. 4 and 5
4 is a perspective view showing such an erasing head. In FIG. 4, the portions common to FIG. 1 are denoted by the reference numerals of FIG. 1 plus “10”.

In the example of FIG. 4, the center core 11 is connected to the coil 15
The side cores 12, 13
(The same structure as the side cores 2 and 3 in FIGS. 2 to 3), and only the upper portion 11b facing the magnetic gaps 14 and 14 has the same laminated structure as the center core 1 in FIGS. , 11a are joined to 11b to form a center core
I have 11. By doing so, the manufacture of the center core becomes easy.

FIG. 5 is a perspective view showing an erasing head composed of a back core and a front core.

The back core 21 is mountain-shaped, has a center core portion 21a around which a coil is wound, and side core portions 21b and 21c on both sides, and is integrally molded. The front core includes a center core portion 30 and side core portions 22 and 23. The center core portion 21a of the back core 21 is joined to the center core portion 30 of the front core, and the side core portions 21b and 21c of the back core 21 are joined to the side core portions 22 and 23 of the front core, respectively.

The center core portion 30 of the front core has the same laminated structure as the center core 1 shown in FIGS. 2 and 3, and the side cores 22 and 23 have the same laminated structure as the side cores 2 and 3 shown in FIGS. In this example, manufacturing of the core is much easier than in the example of FIG.

The above examples are all examples of double-gap type erase heads, but the present invention is also applicable to single-gap type erase heads having a magnetic gap at one location. FIG. 6 is a perspective view showing a single-gap type erasing head.

In this erasing head, a pair of U-shaped cores 31 and 32 are joined to each other at their bases, and a magnetic gap 34 is formed between the end faces of the cores on the side opposite to the bases, thus forming the entire core. . One core 31 is composed of an L-shaped portion 31a around which the coil 35 is wound, and a laminated body portion 31b joined on the portion 31a. The other core 32 includes an L-shaped portion 32a and a laminated body portion 32b joined on the L-shaped portion 32a.
It consists of

The laminated body portion 31b has the same laminated body structure as the center core 1 in FIGS. 2 and 3, and the laminated body portion 32b has the same laminated structure as the side cores 2 and 3 in FIGS. Then, a magnetic gap is formed between the two laminated body portions 31b and 32b.
34 is formed. Either one of the core 31 and the core 32 or both of them may have a laminated structure.

In all of the above embodiments, at least the portion of the core facing the magnetic gap has a laminated structure, but in the following embodiments, at least the portion of the center core and the side core facing the magnetic gap is completely removed. This is an example in which different magnetic materials are used to suppress heat generation due to eddy current and to ensure an excellent erasing rate.

FIG. 7 is a perspective view of the erasing head, and FIG. 8 is a perspective view of FIG.
It is a VIII-VIII sectional view taken on the line. In this erasing head, the material of the center core 41 around which the coil 45 is wound is a low loss material (ferrite in this example), and the C-shaped side cores 42 and 43 sandwiching the center core 41 are made of high saturation magnetic flux density material (this In the example, it is composed of sendust or amorphous).
In the figure, 44 and 44 are magnetic gaps.

In this example, since ferrite, which is a low-loss material, is used as the material of the center core 41, which is the core of the winding portion that is most likely to generate heat, eddy current is hardly generated and the center core 41 generates heat. There is no loss, and there is little loss. Since the side cores 42 and 43 are made of sendust (or amorphous magnetic alloy), which is a high saturation magnetic flux density material, the jaw portion (gap part) of the side core that is magnetically saturated earliest in the erase head is magnetically saturated. It is difficult to do and guarantees a good erase rate.

Therefore, the head of this example has both a high erasing rate equivalent to the case where the entire core is made of a high saturation magnetic flux density material and a heat generation prevention effect equivalent to the case where the entire core is made of a low loss material. Can be made. Even if eddy currents are generated in the side cores 42 and 43 and heat is generated due to the eddy currents, the magnetic recording medium is less damaged than in the case where the center core generates heat.

9 and 10 are sectional views similar to FIG. 8, showing an erasing head using a core composed of a back core and a front core.

In the example of FIG. 9, the back core 51 made of ferrite is formed in a mountain shape, and the center core portion 51a has a coil.
55 is wound. The front core has a center core portion 60 made of ferrite and sendust (or amorphous magnetic alloy)
It is composed of side core parts 52 and 53.

The center core portion 51a of the back core 51
The center core portion 60 of the front core is joined to the upper end of the front core, and the side core portions 52 and 53 of the front core are joined to the upper ends of the side core portions 51b and 51c on both sides of the back core 51, respectively.
In the figure, 54 and 54 are magnetic gaps.

In the example of FIG. 10, the back core 61 made of sendust (or amorphous magnetic alloy) is formed in a mountain shape, and the coil 65 is wound around the center core portion 61a. The front core includes a center core portion 70 made of ferrite and side core portions 62, 63 made of sendust (or amorphous magnetic alloy).

The center core portion 61a of the back core 61
The center core portion 70 of the front core is joined to the upper end of the side core portions, and the side core portions 62 and 63 of the front core are joined to the upper ends of the side core portions 61b and 61c on both sides of the back core 61, respectively. In the figure, 64 and 64 are magnetic gaps.

In both the example of FIG. 9 and the example of FIG.
The front core center core parts 60, 70 are made of low-loss ferrite, and the front core side core parts 52, 53, 62, 63
Sendust (or amorphous magnetic alloy) with high saturation magnetic flux density
Since it is manufactured, substantially the same effect as in the above-described examples of FIGS. 7 and 8 can be obtained.

Although the embodiments of the present invention have been described above, the shape of each part constituting the core may be an appropriate shape other than the above-mentioned embodiments, and the core material may be made of any other suitable high saturation magnetic flux. A density material or a low loss material may be used.

[0047]

In the erase head according to the first aspect of the present invention, the width of the magnetic gap between the magnetic layer and the non-magnetic layer is at least at the magnetic gap side tip of the wound core portion. Since it has a structure in which layers are alternately laminated along the direction, the presence of the non-magnetic layer near the magnetic gap suppresses heat generation due to the eddy current generated in the magnetic layer, and damages the magnetic recording medium. Never give. Further, since the magnetic layers and the non-magnetic layers are alternately laminated, fringing occurs to cause the magnetic flux to uniformly flow in the core, so that the erasing is surely performed.

In the erasing head according to the second structure of the present invention, at least the tip of the wound core portion on the magnetic gap side is made of a low loss material, and the core portion other than the low loss material portion is highly saturated. Since it is made of a magnetic flux density material, the presence of a portion made of a low loss material suppresses the temperature rise near the magnetic gap and does not damage the magnetic recording medium. Moreover, the use of a high saturation magnetic flux density material ensures reliable erasure and high reliability.

[Brief description of drawings]

FIG. 1 is a perspective view of an erasing head according to an embodiment.

FIG. 2 is an enlarged plan view around the magnetic gap.

FIG. 3 is a partially enlarged view of FIG. 2 for explaining the flow of magnetic flux in the magnetic gap.

FIG. 4 is a perspective view of an erasing head according to another embodiment.

FIG. 5 is a perspective view of an erasing head according to another embodiment.

FIG. 6 is a perspective view of an erasing head according to another embodiment.

FIG. 7 is a perspective view of an erasing head according to another embodiment.

8 is a sectional view taken along line VIII-VIII of FIG.

FIG. 9 is a cross-sectional view of an erasing head according to another embodiment.

FIG. 10 is a cross-sectional view of an erase head according to still another embodiment.

FIG. 11 is a cross-sectional view of a conventional erasing head.

[Explanation of symbols]

1, 11, 41 ... Center core 2, 3, 12, 13, 42, 43 ... Side core 4, 14, 24, 34, 44, 54, 64 ... Magnetic gap 6, 8 ... High saturation Magnetic flux density material layer 7 ... Non-metal non-magnetic material layer 9 ... Insulating layer 11b ... Center core laminate portion 21, 51, 61 ... Back core 22, 23, 52, 53, 62 , 63 ... Side core portion of front core 30, 60, 70 ... Center core portion of front core 31, 32 ... Core 31b ... Laminated portion of core 31 MF ... Magnetic flux

Claims (7)

[Claims] 1. A laminated structure, in which a magnetic layer and a non-magnetic layer are alternately laminated along a width direction of the magnetic gap, at least a tip portion of the wound core portion on the magnetic gap side. Erasing head. 2. The nonmagnetic layer has a thickness of 50 μm or less,
The erase head according to claim 1, wherein the ratio of the thickness of the magnetic layer to the thickness of the non-magnetic layer is (1: 1) to (4: 1). 3. A center core portion and a side core portion are provided,
The erasing head according to claim 1, wherein the wound core portion is the center core portion. 4. The erasing head according to claim 1, further comprising a front core portion and a back core portion, wherein the center portion of the front core portion has the laminated structure according to claim 1. 5. An erasing head, wherein at least a tip portion of a wound core portion on a magnetic gap side is made of a low loss material, and a core portion other than the low loss material portion is made of a high saturation magnetic flux density material. 6. The erase head according to claim 5, further comprising a front core portion and a back core portion, and a center portion of the front core portion is made of a low loss material. 7. The erasing head according to claim 5, further comprising a front core portion and a back core portion, and a center portion of the front core portion is made of a low loss material.